1. Field of the Invention
The present invention relates to a recording medium, such as a disc, that has a plurality of information recording layers and on which data can be rewritten; a recording and reproduction apparatus; and a recording and reproduction method, which are compatible with the recording medium.
2. Description of the Related Art
As optical recording media capable of optically recording and reproducing information, optical discs, optical cards, and the like are known. Information is recorded on and reproduced from these optical recording media by using laser light of a semiconductor laser, etc., as a light source and by radiating a very finely focused optical beam via a lens.
In these optical recording media, technology for increasing the recording capacity further has been actively in development. The density of information recorded on a conventional optical disc has been made higher with a view to increasing the recording density on the disc recording surface. For example, attempts for narrowing the track pitch and for increasing the recording density in the direction of the linear velocity in recording and reading scanning have been performed in combination with a shortening of a wavelength of a light source for emitting a recording beam and signal processing of the reproduction system.
However, the shortening of a wavelength of a light source has a limit, that is, up to the ultraviolet region, and the pit size can only be reduced up to the size at which a transfer can be performed on the disc during cutting. As a result, the attempts for increasing the recording density will reach a limit at some future time in the two-dimensional area of the disc.
Accordingly, a technique for achieving a larger capacity has also been considered in a three-dimensional manner. That is, a multilayer disc which is formed in such a manner that information recording layers are layered to increase the density of recording information in the thickness direction of the disc has attracted attention.
The multilayer recording medium in which recording layers are layered have features such that the recording capacity can be doubled according to the number of recording layers and are easy to combine with another high-density recording technology. The multilayer recording media have already been put into practical use as, for example, a DVD (Digital Versatile Disc)—ROMs, which are read-only optical discs.
For example, in U.S. Pat. Nos. 5,682,372, 5,740,136, 5,793,720, and 6,424,614, the configuration of a read-only optical disc having two recording layers, and technology which can be applied to a case in which such an optical disc is recorded and reproduced, have been disclosed.
For the future, in addition to ROM (Read-Only-Media)—type discs, recordable multilayer recording media, in which recordable recording layers of phase-change material, magneto-optical material, die material, etc., are layered, are expected to become commercially practical. For example, speaking of DVD-system discs, realization of multilayer recording layers are also expected in write-once discs called DVD-R, DVD+R, etc., or in rewritable discs called DVD-RW, DVD+RW, DVD+RAM, etc.
In dual-layer discs, as a data recording and reproduction method in each recording layer thereof, a method called a “parallel track path” and a method called an “opposite track path” are known. These methods will be described later with reference to FIGS. 4A, 4B, 5A, and 5B. The opposite track path is such that the address advancing direction is the opposite direction between odd-numbered recording layers and even-numbered recording layers. For example, in the first layer (layer 0), recording or reproduction is performed from the inner area toward the outer area, and thereafter, in the second layer (layer 1), recording or reproduction is performed in loopback from the outer area toward the inner area.
The area structure in a dual-layer disc in the opposite track path is schematically shown in part (a) of FIG. 16. First, in the layer 0, which is the first layer, a lead-in zone is formed in the inner area, and following it, a data zone in which user data is recorded is formed. In this data zone, recording or reproduction is performed from the inner area toward the outer area.
The largest usable address as the data zone (the address in the outermost area where user data recording is possible in the layer 0) is determined in advance, and user data recording is performed up to a required address with the maximum address being the limit. In part (a) of FIG. 16, the address of the end where user data recording is performed in the layer 0 is shown as address UD-END #1.
After reaching this address UD-END #1, the user data recording proceeds to the layer 1, and this time, the recording is performed from the outer area toward the inner area. In the layer 1, the area inner of the end of user data recording is assumed to be a lead-out.
The address UD-END #1 is an address as a position where the recording proceeds from the layer 0 to the layer 1, that is, as an inter-layer transition position.
As shown in part (a) of FIG. 16, in the range which is the area outer from the address UD-END #1, which is an inter-layer transition position, a middle area is formed in both the layers 0 and 1. This middle area has a function as a guard area in which dummy data is recorded continuously to the outer-area end portion where user data is recorded. For example, in a read-only device intended for a ROM-type disc (embossed pit disc), if a non-recorded area where pits are not recorded exists when a recordable disc is loaded, tracking cannot be applied accurately, and a malfunction occurs. For this reason, by considering playback compatibility, a middle area, which is made to be a recorded area by dummy data, is formed.
Here, a data rewritable disc will be considered. In the rewritable disc, for example, as shown in part (a) of FIG. 16, even after the user data #1 is recorded, the content can be deleted to newly write data.
Part (b) of FIG. 16 shows an example in which user data #1 of part (a) of FIG. 16 is deleted so as to be rewritten with user data #2. Part (c) of FIG. 16 shows an example in which user data #1 of part (a) of FIG. 16 is deleted so as to be rewritten with user data #3.
For example, in an example in which the data is rewritten as in part (b) of FIG. 16, the inter-layer transition position moves to address UD-END #2. Furthermore, in an example in which the data is rewritten as in part (c) of FIG. 16, the inter-layer transition position moves to address UD-END #3.
The inter-layer transition position is not constant as in the above-described examples of parts (a), (b), and (c) of FIG. 16 because the position is made the maximum address specified in the disc format, and also, the position is changed according to the amount of user data to be recorded and from instructions from the host (application).
For example, if the address UD-END #3 of part (c) of FIG. 16 is specified as the maximum address at which the user data can be recorded, as shown in parts (a) and (b) of FIG. 16, inter-layer loopback is sometimes performed at address having a smaller value than the maximum address.
That is, part (a) of FIG. 16 shows a case in which the layer 0 is not used up to the maximum address at which the user data can be recorded, and the recording proceeds to the layer 1. Part (b) of FIG. 16 shows a case in which, when user data #1 of part (a) of FIG. 16 is rewritten with user data #2, inter-layer loopback is performed at a lower address. Part (c) of FIG. 16 shows a case in which, when user data #1 of part (a) of FIG. 16 is rewritten with user data #3, inter-layer loopback is performed after the user data is used up to the maximum address of the layer 0, at which the user data can be recorded.
Depending on such user data rewriting, the range of the middle area varies.
On the other hand, in each area (lead-in, data zone, lead-out, middle area), in each sector forming the area, information as zone type indicating area attributes is recorded. This allows each area to be distinguished.
For example, in each sector serving as a lead-in zone, it is shown in the header information thereof that the sector is a sector forming a lead-in zone. Furthermore, in each sector in the data zone, the header information indicates that the sector is a sector forming the data zone. The same applies to the lead-out and the middle area.
Here, it is understood that, when the range of the data zone and the middle area change due to the variation of the inter-layer loopback position in the manner described above, it is necessary to rewrite the header information of the sector according to the change so as to form a new middle area.
When a change is made from part (a) of FIG. 16 to part (b) of FIG. 16, it is necessary to rewrite the attributes of the sector contained in the range A in the figure from the data zone to the middle area. Furthermore, when a change is made from part (a) of FIG. 16 to part (c) of FIG. 16, it is necessary to rewrite the attributes of the sector contained in the range B in the figure from the middle area to the data zone.
Here, the process for rewriting the attributes of the sector contained in the range B in the figure from the middle area to the data zone as shown in part (c) of FIG. 16 is realized by the user data recording itself. That is, since sector recording of the attributes as the user data is performed in the sector which was a middle area, it is not necessary to go through the trouble of rewriting the attribute information of the sector later.
However, the process for rewriting the attributes of the sector contained in the range A in the figure from the data zone to the middle area as shown in part (b) of FIG. 16 must be performed separately from the user data recording. For this reason, the process is performed when a special operation is required, for example, after the user data recording is completed. For example, it is a case in which a finalizing process is performed.
At the time of finalization, processes for finally updating the management information in a lead-in by determining the user data at that time and forming a lead-out are performed. The middle area is also formed if necessary according to the state of the user data recording at that time. That is, a state is reached in which the area after the inter-layer transition position UD-END is correctly a middle area.
In the case of a rewritable disc, unlike a write-once disc, even if it is finalized once, data rewriting thereon is possible.
As described above, since the middle area is formed (the formation of the middle area according to the current inter-layer transition position UD-END), for example, during a specific process such as a finalizing process, there is a time difference from when the user data is recorded until the formation of the middle area in accordance with the user data recording state, and in some cases, the disc before the middle area is formed is ejected from the device. Also, there are cases in which the disc exists in which the middle area in accordance with the user data recording state is not formed due to the operation of turning off the power, power stoppage, etc., during that time.
Due to the above situation, for example, when a finalizing instruction is issued from the host device to the loaded disc, the recording and reproduction apparatus confirms whether or not the middle area (the middle area corresponding to the current inter-layer transition position UD-END) is not yet formed and forms a middle area if necessary.
However, when even the state in which the disc is ejected while the middle area is not formed in the manner described above or even the state such as power stoppage is considered, for determining whether or not the middle area has already been formed, it is necessary to actually access the position at which the middle area should be present in order to reproduce all the middle areas in each layer and to confirm whether or not it is made actually the middle area. Thus, this is a process which takes a very long time.
For this reason, a problem arises in that a processing time including the confirmation of the middle area, such as finalization, becomes longer.